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6 sp manual downshifting effect mpg?

Discussion in 'Technical Chat' started by MMazz365, Apr 8, 2011.

  1. MMazz365

    MMazz365 [OP] Well-Known Member

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    I have a 2010 trd off road 6 speed manual and I downshift to every stop and slow down. Recently I've been trying to get rid of my lead foot but I still see I'm blowing through gas like no other... down downshifting effect this?
     
  2. hudhawk

    hudhawk #texasforever

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    Considering downshifting will raise rpms, and at higher rpms the engine burns more fuel, i would think so. I also drive a trd offroad w/ 6spd manual, given it is an 05, not an 11, but i would think it would be the same. I stopped downshifting to slow down when im driving around town and started taking it out of gear and using the brake to slow down. My mpgs went up a little. What are you currently getting in terms of mpgs?
     
  3. MMazz365

    MMazz365 [OP] Well-Known Member

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    Honesty idk but it has to be low bec I need to fill up every 3 days at least. I wanna invest in ( I forget the name) that computer that will tell you
     
  4. hudhawk

    hudhawk #texasforever

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    Its called a scanguage. Every 3 days is pretty bad, lol. I can usually make it a week on one tank, that is unless my 18 year old go fast mechanism kicks in, haha.
     
  5. whippersnapper02

    whippersnapper02 Well-Known Member

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    Most if not all modern vehicles are designed to shut down the fuel injectors when coasting. Some have said the still notice injector activity with their scangauges when coasting but at a reduced rate. So yes you save fuel by downshifting.
     
  6. MMazz365

    MMazz365 [OP] Well-Known Member

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    Lol that's what its called... and haha that's what I'm trying to eliminate, my 18 yr old fast mechanism lol
     
  7. MMazz365

    MMazz365 [OP] Well-Known Member

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    Did you mean I save gas by downshifting?
     
  8. whippersnapper02

    whippersnapper02 Well-Known Member

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    Yes and it helps you slow down. I was taught to always downshift.
     
  9. thinkingman

    thinkingman Well-Known Member

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    Foglights are for fog, not oncoming traffic!
    Downshifting neither helps you slow down or save fuel.
    Add another to the TW misinformation machine.
    The only benefit is to the mechanic that will be replacing your clutch at a much-too-early interval.
    You guys kill me.
     
  10. steve o 77

    steve o 77 braaap

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    It does help you slow down. Have you ever had the truck in 4low going down a steep incline just coasting in 1st gear? you don't even have to use the brakes because the compression of the engine keeps the speed constant.

    Now I agree downshifting to slow down at every light is kinda stupid unless you're able to perfectly rev match the engine on every shift because you will kill the clutch sooner.
     
  11. jrider636

    jrider636 Well-Known Member

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    so true and lmao
     
  12. skytower

    skytower Well-Known Member

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    Hmmm... I have to call BS. Downshifting, also known as Engine Braking, has a significant effect on deceleration. Fuel savings, however, is still debatable.
     
  13. whippersnapper02

    whippersnapper02 Well-Known Member

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    So I guess you never heard of engine braking?

    Also yes it saves fuel. Search anywhere for the injector shutdown and you will see that most if not all modern vehicles have this feature. Also if it is fake then why does the scangauge have a setting for injector shutdown?
     
  14. MMazz365

    MMazz365 [OP] Well-Known Member

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    For a fact, downshifting helps me slow down significantly
     
  15. macgyver

    macgyver Well-Known Member

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    Actually, Complete misinformation on your part sir

    Downshift DOES slow you down and DOES NOT wear your clutch any faster if done properly.

    I downshift all them time and always have in every manual vehicle I have driven.

    Explain to me why when rolling down a hill in 1st gear as opposed to nuetral I go slower?
    Why do I spin out of control on an icy hill coasting in nuetral using my brakes but I don't when I'm slowly crawling down the hill in 1st gear without using my brakes?
    Ever descended a hill in 4LO in first gear? When I offroad I rarely have to use my brakes descending hills because I can crawl down in 1st gear without touching my brakes.
    Why are there signs on the side of road in mountains telling truckers to use a lower gear?

    to the OP, when decellerating you actually use less fuel than if you were coasting in nuetral, then transfer of power through the driveline keeps the engine turning as opposed to in nuetral your engine would require fuel to keep it idling.

    For example, in my last car I had a wideband 02 readout on my dash because I wanted to monitor my AFR's since I was turbo'ed. When I would downshift, my wideband readout would show "LEAN" when decellerating in gear. If I coasted and used my brakes, my wideband readout would display around 14.7 (stoich). This means I was using LESS fuel downshifting than if I coasted in nuetral. RPM's aren't the only indicator of fuel consumption.

    One might actually use more fuel doing 20mph in 5th gear @1500rpm as opposed to running 20mph in 3rd @ 3000rpm because the engine is under more load at 20mph in 5th gear which requires more fuel to keep it from stalling.
     
  16. Foihdzas

    Foihdzas What is hummingbird?

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    I always downshift when coming up to a light, going down steep grades ect... although it does not give me a huge deceleration, it does help. I do agree with thinkingman about premature clutch wear, so do not downshift aggressively, ( 5th to 3rd, then 3rd to 1st kind of thing) so I do not wear my clutch out too badly.

    my 0.02
     
  17. hudhawk

    hudhawk #texasforever

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    I'd much rather buy new brake pads than a new clutch
     
  18. whippersnapper02

    whippersnapper02 Well-Known Member

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    If you can drive a manual properly you won't wear the clutch any faster. Also most wear occurs when taking off from a stop.
     
  19. thinkingman

    thinkingman Well-Known Member

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    Foglights are for fog, not oncoming traffic!
    If you read the posits in the OP, and you have experience in the matter, you'll find that downshifting to a stop and maintaining speeds on downgrades are two entirely different matters.
    In re downshifting, I'd be willing to bet less than 10% of the people on this thread know how to heel and toe properly and if you're trying it in a Tacoma, it's a raging fail, with the brake/clutch/accelerator and sloppy-ass shifter.
    I learned to heel and toe in a Formula Ford and promise you, it wasn't for slowing the car.
    Creeping downhill in 4wd is not the same as the OP.
    No it's not.
    Trucks using lower gears to control forward momentum on downgrades is not the same as the OP...some may use an exhaust brake for additional control, but that's a different kettle of fish.

    Why do I spin out of control on an icy hill coasting in nuetral using my brakes but I don't when I'm slowly crawling down the hill in 1st gear without using my brakes?
    Because you're not a very good driver and lack basic car control knowledge.
    Low friction surfaces require very light inputs if you're nearing maximum traction. I know, without a doubt, I can modulate my brakes quicker and with more precision, than I can modulate the throttle, especially if I have to alternate between a closed throttle and an open one....in your example I italicised above, you're adding drivetrain backlash into the equation.....epic fail in low traction/downhill circumstances.
    Stick to the example by the OP, not your own.
     
  20. whippersnapper02

    whippersnapper02 Well-Known Member

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    Just FYI, this whole thread is about slowing down not matching revs while shifting.
     
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